Witzend. "Don't do that, or the library lady will be cross."
That reminded me of a time when a child was misbehaving in the Post Office queue. A policeman was just behind them, and the child's mother told her to behave, or "the policeman will take you away."
The policeman gave her a good telling-off, saying that the child might need help, one day, and be afraid to approach a policeman because of her words.
Of course, these days, we rarely see any police about to help anyone!
Reference the subject of children screaming while playing, I agree that they should be trained to be more considerate. We were never allowed to make excessive noise. We did, however, use the house wall at the end of the street to play ball games against. The thudding probably annoyed the occupants, but we never gave it a thought, at the time, and they never complained.